1. Field of the Invention
The invention of this application relates to the field of manufactured articles having the characteristics of natural articles. More particularly, this invention relates to methods and apparatus for producing a plastic article with some of the contours and colors of natural articles, and then employing a unique process to imbue the plastic article with corners, edges, and shapes not found in those natural articles, thereby creating a master part representing a state of the art previously unknown, and using this master part to manufacture plastic reproductions in commercial quantities.
2. Discussion of the Background
Many people have attempted to manufacture plastic parts simulating the contours and colors of natural articles, but either produce an item that does not look authentic or that poorly reproduces the natural article in its entirety. One example is Formica®, a hard plastic substrate used to cover countertops and the like. Some forms of Formica® were impregnated during manufacture with dyes or other colored material to simulate the look of wood or stone. But the simulation was not convincing because the Formica® was flat. It did not have the texture of the natural articles it purported to simulate.
Another example is Corian®. This was made from plastic in the form of sheets of varying thickness for use as countertops and related structures. The resulting product was colored much like the filler material used during manufacture. Some forms of Corian® were made to resemble stone. But the simulation was not convincing because Corian® was largely flat. It did not have the texture of the natural articles it purported to simulate.
Yet another example is Linoleum®. This was made from various plastics and fillers, and was sold in the form of sheets or rolls, principally for covering floors with a wear-resistant surface. While some forms of Linoleum® were colored and textured to resemble natural articles, the simulation was not convincing. The colors were artificial and the texture so regular as to dispel the notion of a natural article.
Still another example is plastic floor tiles. These were typically squares of regular size. They were intended to be butted against one another once a mastic had been applied, and some were both colored and textured to resemble natural articles. However, the colors were often unconvincing. And the same was true for the textures, which were not only shallow, but also discontinuous where one tile butted up against another.
Another example is exterior siding designed to replace or cover some or all of the exterior of outdoor structures, including houses. This siding typically was made of plastic or aluminum and was marked or embossed in an effort to simulate natural articles. But the simulation was not convincing. The colors were unconvincing and the textures were not only shallow and unrealistic, but also discontinuous where one piece of siding butted up against another.
Another example is cultured stone. This was cast from cement and aggregate and simply mimicked the characteristics of real stone. It could not be molded any differently from the natural article, and required the same methods for installation as real stone.
Processes for casting plastics are disclosed in U.S. Pat. No. 5,750,583 to Gansen et al. and U.S. Pat. No. 3,883,627 to Fitts. Gansen et al. disclosed a process for the preparation of polyurethane products in which a plastic film was positioned in a mold, the mold was closed, a polyurethane reaction mixture was injected into the mold, and the product was removed from the mold once the reaction mixture had fully reacted.
Fitts disclosed a process in which a heat curable elastomeric sheet comprising a curing agent and either urethane elastomeric gum stock or silicone gum stock was placed over a master to be copied; the heat curable elastomeric sheet was one that did not cause inhibition between the master and the heat curable elastomeric sheet. Next, the elastomeric sheet was vacuum drawn against the master and the master sheet material was enclosed in a frame. Next, a foamed polymeric backing was formed in situ to force the heat curable elastomeric sheet against the master to copy the shape of the master in the heat curable elastomeric sheet, which was then cured in the shape of the master. Finally, articles were molded in the shape of the master in a mold constructed from the cured elastomeric sheet material.
A decorative plastic moulding was disclosed in U.S. Pat. No. 5,372,869 to Drexinger et al. The moulding comprised two moulding pieces, each with a decorative face, a back, two sides and two ends. Each end of each piece had a 45 degree angle pre-mitered cut relative to the plane of the decorative face, with the pre-mitered cuts of each piece being in parallel planes. Each side of each piece was in a plane at a 45 degree angle to the plane of the decorative face, with the side planes converging at a position spaced from the back of the piece. The two moulding pieces were made of fire rated polyurethane.
Finally, a method for molding an artificial rock was disclosed in U.S. Pat. No. 4,940,558 to Jarboe et al. This method entailed selecting a rock for reproduction, creating a flexible rubber mold and supporting cradle having a mold cavity conforming to the exterior of said rock, the mold having a substantial degree of flexibility and being created by applying an uncured liquid rubber forming material to said rock, curing the uncured liquid rubber forming material to produce the rubber mold, the cradle being formed by applying by spraying a low density urethane foam forming mixture to the exterior of the rubber mold to provide a self-supporting cradle, spraying a two-sided urethane composition into the mold cavity, said urethane composition comprising an isocyanate side and a polyol side and being mixed in a spray gun in a spray-in-mold process, carrying out the spraying to build up the molded artificial rock to a desired thickness and stripping the cradle and mold after curing.